Japanese patent application laid-open No. 5-291627 discloses a reflection-type light emitting apparatus in which an LED (Light Emitting Diode) element is located opposite to a reflection mirror so as to reflect light emitted from the LED element and emit the reflected light in a desired direction. The reflection-type light emitting apparatus has a problem that part of light is blocked by the LED element and a lead for power supply that are located on an optical path of reflected light, although it has good light radiation efficiency since the reflection-type light emitting apparatus can focus light in high efficiency.
LED's with high output are recently developed along with increasing applications of LED, and LED's of large output type such as several watts are already on the market. Although LED's are characterized in its less heat generation, in order to provide LED with high output, a large amount of electric current needs to be supplied to the LED element. As a result, a considerable amount of heat generation occurs in the LED element.
The light emitting apparatus disclosed in Japanese patent application laid-open No. 5-291627 is composed such that the LED element is mounted on a lead, an electrode of the LED element and the lead are wire-bonded and sealed with a first light transmitting material, and the first light transmitting material and the lead are sealed with a second light transmitting material. The second light transmitting material has a concave reflection surface formed opposite to the light emitting surface of LED element and has a flat radiation surface formed on the backside of the LED element. Light emitted from the LED element is reflected on the concave reflection surface and then the reflected light is radiated from the radiation surface to the outside of light emitting apparatus.
In the conventional reflection-type light emitting apparatus, heat generated when turning on the LED element is transferred and radiated through the lead to the outside. However, if the lead is enlarged to cope with an increase in heat generation, light emission efficiency of the apparatus must lower since the reflected light is blocked by the enlarged lead. Thus, there is a barrier in enhancing the light emission efficiency.
It is an object of the present invention to provide a reflection-type light emitting apparatus that has an excellent heat radiation performance and can minimize a reduction in emission efficiency of reflected light.
It is a further object of the present invention to provide a reflection-type light emitting apparatus that has a reduced number of components.